Video Transcript
The difference in electronegativity between two atoms of different elements is 0.2, using values from the Pauling scale. What type of bond is likely to form between these two atoms in a chemical reaction? (A) An ionic bond, (B) a polar bond, (C) a nonpolar covalent bond.
This is a question about electronegativity, which is defined as the tendency of an atom to attract a bonding pair of electrons. When two atoms form a bond between them, the electrons involved in that bond will be attracted to each of the two nuclei. The more electronegative atom will pull the electrons closer to its nucleus. Depending on the difference in electronegativity between the two atoms, the electrons will be distributed in different ways, resulting in different kinds of bonds. Let’s describe the difference in electronegativity and the arrangement of electrons for each of the three answer choices.
An ionic bond forms when the difference in electronegativity is greater than 1.7. Ionic bonds are often formed by the donation of electrons from the less electronegative atom to the more electronegative atom. The high difference in electronegativity means the electrons are given away rather than shared. However, it is worth noting that an ionic bond can also form between two ions that have already donated or received electrons.
A polar bond forms when the electronegativity difference is between 0.4 and 1.7. In a polar bond, the electrons are unevenly shared. There is a moderate difference in electronegativity. So the more electronegative atom will pull the electrons more closely to its nucleus.
Lastly, a nonpolar covalent bond forms when the difference in electronegativity is less than 0.4. This small difference in electronegativity means that neither atom pulls the electrons more strongly than the other. As a result, the electrons are evenly shared in between the two atoms.
The two atoms in the question have an electronegativity difference of 0.2. 0.2 is less than 0.4. So the bond that will form in this situation is a nonpolar covalent bond, represented by answer choice (C), the correct answer. Since the electronegativity difference between these two elements is quite small, atoms of these two elements will evenly share their electrons in a nonpolar covalent bond. So, what type of bond is likely to form between these two atoms in a chemical reaction? That’s choice (C) a nonpolar covalent bond.
